The old question about the tree falling in the forest and nobody being there to hear it was, I thought, a mind puzzle from India … like the question of the sound of one hand clapping. But it turns out that the “falling tree” metaphysical query was first posed by George Berkeley, in his work, A Treatise Concerning the Principles of Human Knowledge (1710).

The sound of one hand clapping does appear, however, to be a traditional zen koan.